1. Field of the Invention
The invention pertains to stripline couplers and more particularly to interlevel stripline couplers for coupling between levels of multilevel stripline circuits.
2. Description of the Prior Art
Many stripline circuits require strip conductors in a common plane to cross, thus establishing crossovers that are difficult to effectuate in a one level stripline configuration. In the prior art, these crossovers are generally accomplished with multilevel stripline circuits and interlevel connections. A multilevel system is designed and one of the crossing lines is transformed to another level to effectuate the crossing, thus establishing a need for interlevel coupling. Prior art systems utilized metal connecting pins between the levels on which the striplines to be connected are located and soldering the striplines center conductors to these interlevel connecting pins. This operation is difficult and presents many assembly problems. Additionally, the resulting connections generally cause amplitude and phase variations to occur to the signals coupled. For many applications these amplitude and phase variations are within tolerance limits and acceptable performances are provided. In applications, however, wherein extremely tight tolerances are required, the random phase shifts and junction losses realized through a multiplicity of interlevel connections adversely affect the network responses and unacceptable performances result. What is required is an interlevel coupling system that eliminates the interlevel connecting pins and the soldering thereto.